Worksheet: Kinetic Energy

In this worksheet, we will practice calculating the kinetic energy of an object moving relative to an observer given its mass and velocity.

Q1:

A bullet of weight 8.0 g has a speed of
800 m/s.

What is its kinetic energy?

What is its kinetic energy if the speed is halved?

Q2:

How fast must an elephant with a mass of 3,000 kg move to have the same kinetic energy as a sprinter with a mass of 65.0 kg running at 10.0 m/s?

Q3:

You are launching a 2.0 kg potato out of a
potato cannon. The cannon is 1.5 m
long and is aimed 30 degrees above the
horizontal. It exerts a 50 N force on the potato.
What is the kinetic energy of
the potato as it leaves the muzzle of the potato cannon?

Q4:

An aircraft carrier has a mass of 78,560 tons and moves at a speed
of 24 nautical miles per hour.
What is the kinetic energy of the aircraft carrier?

Q5:

An automobile of mass 2.00×10 kg has a velocity of
1.00×10 km/h,
a runner of mass 80 kg has a velocity of
10.0 m/s,
and an electron has a velocity of
2.0×10 m/s.

What is the kinetic energy of the automobile?

What is the kinetic energy of the runner?

What is the kinetic energy of the electron?

A2.0×10 J

B2.9×10 J

C1.8×10 J

D2.5×10 J

E2.3×10 J

Q6:

An object with a mass of 3.3 kg
has four times the kinetic energy of an object with a mass of
7.4 kg.
What is the ratio of the speed of the object whose mass is
3.3 kg to the speed of the object whose mass is
7.4 kg?

Q7:

A spring has a mass of 10.0 g,
uniformly distributed along its length.
The left end of the spring is fixed.
The right end of the spring is moving in the 𝑥-direction
at 0.125 m/s
and the right end of the spring is at the equilibrium position
𝑥=0.000m.
What is the kinetic energy of the spring?

A3.91×10 J

B2.60×10 J

C1.56×10 J

D2.34×10 J

E7.81×10 J

Q8:

How many times greater is the kinetic energy of an astronaut of mass 72.6 kg and velocity 21,200 km/h
than the kinetic energy of a truck of mass 22,350 kg and velocity 105 km/h?

Q9:

A child is pulling two red wagons, with the second one tied to the first by a (nonstretching) rope. Each wagon has a mass of
5.0 kg.
If the child exerts a force of
40 N for 6.0 m,
how much has the kinetic energy of the two-wagon system changed?

Q10:

If wind is blowing horizontally toward a car at an angle of 30 degrees from the
direction of travel, the kinetic energy of the car will
. If the wind is blowing at a car at 135 degrees from the direction
of travel, the kinetic energy of the car will .

Adecrease, increase

Bincrease, decrease

Cdecrease, decrease

Dremain the same, increase

Eincrease, increase

Q11:

A bullet from a 0.22LR-caliber cartridge has a mass of 2.60 g and a muzzle velocity of 335 m/s.
It is fired and penetrates a door of 1-inch thick (2.54 cm) pine board that generates a stopping force of 120 N.
How fast would the bullet be traveling after it penetrated through the door?

Q12:

What is the kinetic energy of an athlete of mass
80 kg who is running at
10.0 m/s?

Q13:

The Chicxulub crater in Yucatan, one of the largest existing impact craters on Earth,
was created by an asteroid that has been modeled as impacting the Earth traveling at
22 km/s,
dissipating 4.2×10 J of energy. What is
the minimum mass of the asteroid necessary to have done this?

A1.7×10 kg

B8.7×10 kg

C3.4×10 kg

D7.3×10 kg

E3.8×10 kg

Q14:

What is the kinetic energy of a neutron moving at
a speed of 2.2 km/s?

A8.2×10 J

B8.2×10 J

C3.7×10 J

D2.3×10 J

E4.1×10 J

Q15:

A basketball player throws a ball of mass 624 g and
it moves a distance of 15.0 m
in 2.000 s.
What is the ball’s translational kinetic energy while it is moving?

Q16:

A man with a mass of 75.0 kg is in
a subway train car that is moving along some tracks at
15.00 m/s. The man
walks at a speed of 1.500 m/s, first in the same direction as the car’s motion,
and then in the opposite direction to the car’s motion.

What is the man’s kinetic energy relative to the car when he walks in the same
direction as the car’s motion?

What is the man’s kinetic energy relative to the car when he walks in the
opposite direction to the car’s motion?

What is the man’s kinetic energy relative to the tracks when he walks in the
same direction as the car’s motion?

What is the man’s kinetic energy relative to the tracks when he walks in the
opposite direction to the car’s motion?